1. Field of the Invention
The present invention relates to an antenna and, more particularly, to a broadband antenna with a feeding plane.
2. Description of the Related Art
With developments in wireless communications technologies, many electronic devices, such as notebooks and mobile phones, now include wireless communications capabilities. Moreover, with improvements in the integration of wireless communication systems, broadband antennas have become increasingly important. In order to permit a wireless communication device to utilize various frequency bandwidths, antennas having wider bandwidths have become the most significant technology certainly.
However, in wireless communications, the Wireless Wide Area Network (WWAN) antenna and Wireless Fi-delity (Wi-Fi) antenna are very popular and significant transmission devices. In prior art technologies, the working frequency range of a WWAN antenna is usually 824˜960 MHz and 1710˜2170 MHz, and the working frequency range of a Wi-Fi antenna is usually 2.4˜2.5 GHz and 5.15˜5.85 GHz. However, these bandwidths of the antenna do not satisfy current needs. New antennas should be able to have wider bandwidths; for example, to satisfy global positioning system (GPS) frequencies of 1575 MHz and digital video broadcasting-handheld (DVB-H) frequencies 1627 MHz.
In order to satisfy different transmission frequency ranges, the prior art technology discloses an antenna for these portable electronic devices. Please refer to FIG. 1A. FIG. 1A is a schematic drawing of a prior art antenna 90 disclosed in U.S. Pat. No. 6,861,986. The prior art antenna 90 has a radiating element 91, a connecting element 92 and a grounding element 93. The connecting element 92 has a first end 921 and a second end 922; the first end 921 of the connecting element 92 is connected to the radiating element 91; and the second end 922 is connected to the grounding element 93.
Please refer to FIG. 1B. FIG. 1B shows the VSWR at different frequencies according to the prior art antenna 90 shown in FIG. 1A. As shown in FIG. 1B, the working frequency range is only 2.5 GHz and 5 GHz approximately. Therefore, the antenna 90 only satisfies current bandwidth requirements of the Wi-Fi antenna but does not satisfy current bandwidth requirements of the WWAN antenna or other broadband antennas.
Therefore, it is desirable to provide a broadband antenna to mitigate and/or obviate the aforementioned problems.